Recommended chargers for flashing your BMW

When flashing new software to your car, it is important that the voltage be held constant. That stability will ensure there are no problems with writing the data to the very sensitive ECU. Any fluctuations in voltage can cause a “bad write”, and as a worst case, “brick” the ECU.

Voltage drops can be caused by a number of seemingly insignificant things. Opening a door or trunk during a flash can turn on the dome lights, or trigger other chassis functions, which can cause a voltage drop. A heat soaked radiator can trigger the Aux fan to turn on causing a voltage drop. While not all of the possible causes can be prevented, a strong charger can mitigate the possible bad outcomes.